In answer to Petras interest here are some statistics on California earthquakes

Statistics for M>=2 in California (1-1-2000 through 5-12-2001)

A followup to the California earthquake situation. The daily count
of earthquakes from SCSN and NCSN for today (UT May 13) is 1 event.
The only other day with less than 3 events of Ml>=2 since 1-1-2000
was March 6, 2000 with 1 event. The next lowest number per day
were Jan 26, 2001, Oct 23, 2000 and March 5, 2001, each of which
had 3 events of ML>=2.0. The average number of Ml>=2.0 per day
for the state of California since 1-1-2000 is 16.08 with a standard
deviation of 7.99 events/day. 1 event per day is significant at the
0.05 level, 3 at the 0.10 level.

Statistics for M>=3 in California (1-1-2000 through 5-12-2001)

The number of days between events of Ml>=3 in California has varied from 0
to 5 days since January 1, 2000. The longest period between events
of Ml>=3 was 5 days occurring during the periods Feb 14-19, 2000;
Oct 3-8, 2000 and Nov. 25-30, 2000. The average interevent time is
1.49 days with standard deviation of 0.9 days.
The last event in California of Ml>=3 was a Ml 3.1 in the Geysers
on May 5 (8 days ago). The last event in the SCSN (southern California)
catalog of Ml>=3 occurred on April 27, 2001 (16 days ago) near Parkfield.
Given that the longest dry period during the past year and a half
was 5 days and the standard deviation is 0.9 days, an 8 day period
between Ml>=3 for the state and a 16 day period for Southern California
is highly significant in a statistical sense. I think it is safe
to say this is an earthquake drought at these magnitude levels.

Events of M>=3.0 in the Mammoth Lakes/Lee Vining area

To answer Petra's question on earthquakes in the Mammoth Lakes
region. Here are the statistics for Ml>=3 events in that area.
There have been 32 events of Ml>=3.0 listed in the NCSN catalog
since 1-1-2000. Two pairs of these occurred on the same day,
30 days saw events of Ml>=3 during this 497 day period. In other
words there have been no swarms of Ml>=3 during this time. The probability
an earthquake will occur on a particular day with Ml>=3 in the
Mammoth Lakes region is then, 0.06 (about 1 chance in 16).
The average number of days between events of Ml>=3 is 13.48 +/-14.08 (STD).
The longest dry spells between such events in the Mammoth Lakes
area was 53 days between Sept 5, 2000 and Oct 28, 2000 and
54 days between June 22, 2000 and August 15, 2000. The last
event of Ml>=3.0 in the area occurred on May 4, 2001.